Blasting mat



March 5, 1968 PER FOLKE WIKNER ET AL 3,371,604

BLASTING MAT Filed May 26, 1966 n 5? W 5 f. 2% PK M ,8 ATTORNEYS United States 3,371,604 BLASTING MAT Per Folke Wikner and Knut Lundgren, Lidingo, Sweden,

assignors to Curt Fredrik Lundin and Johannes Hans- Udo Elbert Speer, Stockholm, Sweden Filed May 26, 1966, Ser. No. 553,213 Claims priority, application Sweden, May 31, 1965, 7,059/ 65 6 Claims. (Cl. 10222) ABSTRACT OF THE DISCLOSURE The present invention relates to a blasting mat of the type which, after placing an explosive charge, is used to cover the site at which the charge has been laid so as to dampen the subsequent detonation waves and prevent the spreading of rock splinters or other debris.

Blasting mats for this purpose have almost exclusively been formed of motor tires cut up into required lengths. However, blasting mats hitherto used are very easily destroyed by the blast and usually last no longer than one or two blasting operations, thus involving high expenses. Further, due to firstly the heaviness of the material from which the tires are made and secondly because it is necessary to use very thick wire, which in itself is also heavy, to bind the strips of tire together, such mats obtain a considerable weight. Moreover, mats of this type are ditficult to handle and it is the usual practice to employ mechanical excavating machines or the like to move said mats, which is naturally both a drawback and inconvenient.

The object of the invention is to eliminate these drawbacks and is mainly characterized in that the blasting mat is constructed of a number of adjacently lying tubes or hoses joined together by means of Wire which passes through the tubes etc.; reinforcing and binding the same together.

The invention will be more closely described with reference to an embodiment of the same shown diagrammatically in the accompanying drawing; in connection therewith additional features characteristic of the invention being shown.

FIGURE 1 is a perspective view of one end of a blasting mat according to the invention formed of two adjacently positioned mat sections.

FIGURE 2 shows in plan view a method of connecting together two mats or mat sections according to the invention.

FIGURE 3 is a view seen from one end of the mat and illustrates the method of operation of the mat during the blasting operation.

FIGURE 4 shows the way in which the mat can be rolled-up, comfortably and without difiiculty.

FIGURE 5 is a partial perspective view of a blasting mat according to the present invention, with spacers being interposed between adjacent tubes.

Reference is first made to FIGURE 1 which shows in perspective a blasting mat constructed in accordance to the invention. The shown mat is, for instance, built up of two mat sections placed side-by-side and indicated by atent A and B. Each of these sections is formed of a number of tubes 1 and 2, which in the shown example lie closely adjacent to each other. According to the invention, however, it is also possible, if required, to space the tubes at short distances from each other, using suitably designed spacers 20 for the purpose, as shown in FIGURE 5.

For the purpose of holding the tubes in the various sections together, wire-holes are drilled at specific distances from the ends of the tubes 1 and 2, substantially diametrically through said tubes; after which wire slings 3 and 4 are passed through said holes, and the end portions 5, 6 and 7, 8 respectively of said slings, subsequent to tightening said wire, are locked together, for instance, by means of wire locks indicated by reference numerals 18 and 9 respectively. It is often sufficient to use only one wire sling through each mat section but there is nothing to prevent several separate or possibly snake-like continuous wire slings, being used to retain the tubes in their mat section.

The main function of the slings 3 and 4 is to hold the tubes together so that the shape of the mat is retained. However, so that the mats are capable of resisting the enormous stresses to which they are subjected during the blasting operation it has proved necessary, to reinforce the mats in a manner suitable for the purpose. This can be effected by passing the wire longitudinally through the tubes in a snake-like manner. Such reinforced wire is indicated in FIGURE 1 by the reference numeral 10. In this way it is possible to reinforce each mat section per se or to reinforce all the adjacent-lying mat sections by passing the wire 10, as is shown in FIGURE 1 through a tube in the one section and then through the opposite tube in the next section and so on in an endless loop through both or all of the sections of the mat.

To illustrate the alternative of separately reinforcing each mat section per se reference is made to FIGURE 2 which is substantially the same as FIGURE 1 except that the reinforcing wire 11 of the mat section A only passes through the tube 1 in this section while wire 12 passes through the tube 2 in the adjacent lying mat section B. The bends, situated substantially opposite each other, in the Wires of each wire reinforcement 11 and 12 are woven or bound together, for instance by means of an additional wire 13 threaded in said bend.

It is not suitable to use hooks or other securing means to connect the sections together since it is always possible that said hooks etc., or portions of the same, might disintegrate during the explosion, causing an accident. One of the objects of the invention is to manufacture blasting mats which are easy to handle. It is also important that the tubes are manufactured of a material capable of resisting the enormous forces which appear during the explosion. Furthermore, this material should at least have a certain degree of flexibility if the mat is to function in the manner desired. Rock splinters and other debris are prevented from penetrating the compact mat when an explosion takes place but on the other hand certain gaps exist between the tubes; it naturally being possible to predetermine the width of said gaps by inserting suitable spacers 20, threaded onto the wire slings passing through the tubes. When blasting, resulting gas and air can pass through said gaps in a limited fashion; the gaps functioning substantially as valves members. In this way shock waves occurring on detonation are dampened considerably. It is important to the satisfactory functioning of the present invention that the wall of each tube situated adjacent to the gaps is at least somewhat resilient. This, however, can be accomplished by selecting a suitable material with which to manufacture tubes. Preferred flexible materials suitable in the present context are olefin, polymers, rubber etc. These mate- 9 rials, however, are in no way restrictive to the invention since fibre or laminated material can also be used.

To illustrate how a blasting mat according to the invention behaves in principle during the blasting operation reference is made to FIGURE 3 which shows a blasting mat at the instance of blasting; the tubes 1 and 2 in sections A and B (in FIGURE 3) together forming a knee 14 as a result of the blasting effect, represented by the arrows C. It should be noted in this respect that the ends 15 and 16 respectively of the tubes are displaced into each other giving a locking effect. It has been proved that, in spite of the relative lightness of the mat, the pressure forces in the air occurring as a result of the blasting operation also act within the tube holding the mat down to a certain extent. This phenomenon is not fully understood but is probably due to suction forces caused by the vacuum appearing as the blast Waves travel outwards.

Although it is preferred to use tubes which are fully open at the ends it is also conceivable in certain embodiments of the invention to impart to the mats a substantial weight and thereby an increased damping eifect to fill the tubes with a filler of considerable weight, e.g. sand, whereby it is naturally necessary to block the ends of the tubes to prevent the sand from running out.

Blasting mats of previous constructions are formed of cumbersome pieces of motor tires and are practically impossible to coil up into rolls of reasonable diameters. In this respect the invention otters yet another advantage against the status of the art in that the mat according to the invention can be rolled up in a simple manner, as is illustrated diagrammatically in an end view in FIGURE 4. It should be further noted that such a mat can be both easily rolled up or pulled over the ground, something which is most difficult to do with the previously known blasting mats. The weight of the mat can be easily determined by adjusting the thickness of the wires as well as of the tube Wall.

The invention is not restricted to the illustrated and described embodiment of the same but can be arbitrarily varied within the scope of the inventive idea.

What is claimed is:

1. A blasting mat comprising at least one row of tubes extending parallel to each other in each row; at least one rope passing longitudinally through each tube in a tortuous path and transversely through the Walls of said tubes to form a reinforcing rope network lock; said tubes being resilient and lying closely adjacent to one another, and said lock loosely binding said tubes together so that, during blasting, a vent is formed between adjacent tubes for passage of gas and air, while solid debris is retained under said mat.

2. A blasting mat as claimed in claim 1, wherein spacer members are positioned between the tubes and secured by a portion of said rope, the length of said spacer members being less than that of each of said tubes.

3. A blasting mat as claimed in claim 1, wherein the tubes are made of olefin polymers.

4. A blasting mat as claimed in claim 1, wherein the tubes are made of rubber.

5. A blasting mat as claimed in claim 1, wherein a plurality of rows of tubes are arranged unidirectionally side by side, and wherein a separate securing rope is passed in loops through all the tubes in each row of tubes.

6. A blasting mat as claimed in claim 5, wherein an additional rope is provided between adjacent rows of I tubes to bind their respective ropes together.

References Cited UNITED STATES PATENTS 2,926,605 3/1960 Hammel et al 10222 FOREIGN PATENTS 75,264 6/1949 Norway. 

